Annular gaps between tubulars or a tubular string and an open hole have needed seals for a variety of reasons. In most applications the dimensions of the annular gap are fixed and resilient members can be used to span the gap. These seals can come in the form of packer cups that are made to flex to enter the surrounding tubular and are secured to a string being run in through the tubular. Another design is an annular resilient ring that is axially compressed when at the desired location. This can be done in a variety of ways such as setting down weight or applied pressure to a setting piston to name a few ways. An inflatable element can also be used.
Some of the shortcomings of such designs are that they can't accommodate expansion of the tubular to which they are mounted, they suffer from low differential pressure capacity and they have limits on how far they can extend to make a sealing contact with a surrounding tubular.
Other designs have been developed that are essentially resilient rings that expand with the tubular that supports them for an annular seal that seals in opposed directions. Some examples are U.S. Pat. Nos. 7,051,805; 6,959,759; 7,134,504; 7,703,542; 7,886,818 and 7,845,402. These seals are bidirectional and have limits on radial extension based on the tubular to which they are mounted.
Another design is revealed in US Publication 2008/0251250 where a series of overlapping petals 310 are initially retained by a band 314. The petals are connected to tubular 312 that is expanded. The band breaks with expansion of the tubular. The petals can be in a single row but are stated to be preferably in multiple rows. The main issue with this design is the dependency for sealing on petal overlap which can be problematic if the petals do not all move out radially in a uniform fashion.
The present invention describes in detail a seal that can be used in the method described by the inventors in a US application entitled Pump Down Swage Expansion Method filed on Oct. 8, 2010 and having Ser. No. 12/901,122.
The present invention addresses the issues in the prior designs and presents a seal that has a unitary structure and a capability of spanning the annular gap upon tubular expansion. It features a pleated design that has folds over adjacent folds and an optional capability of inserts to further add outward bias to the generally tapered design. A retainer holds the assembly retracted for running in and is defeated on initiation of expansion. Pressure from above the set seal can be used to advance the tubular or centralize it or to push a swage assembly that is connected to the seal. Flow past the seal in the opposite direction is possible so that fluids displaced by cementing or even cement can push past the seal. In an alternative design the cup shaped seal is mounted to the tubular to be expanded and is inserted into a surrounding tubular preferably already in contact with the surrounding tubular on insertion. The expansion of the tubular and the seal enhances the seal against the surrounding tubular by the preferably cup shaped member. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be determined from the appended claims.